1. Field of the Invention
The present invention relates to a data broadcasting system for providing data broadcasting service mainly for mobile unit or portable terminal, and a receiving terminal device used in the system and its peripheral technology.
2. Description of the Related Art
Recently, in the field of television broadcast, ground wave broadcast and satellite broadcast are being digitized and partly realized. However, the existing digital broadcasts are basically directed to fixed terminal devices, and it is technically difficult to provide mobile units and portable terminals with adequate services depending on the status of use. In particular, these broadcast program contents are intended to be reproduced all the same in any terminal device, and part of program contents cannot be selectively reproduced depending on the specification by user, specification by broadcasting station, or condition of use.
On the other hand, there is a mounting need for data broadcasting system for broadcasting multimedia information composed of video, audio and text mainly for mobile units and portable terminals. To realize this need, it is indispensable to solve these problems that have been technically difficult in the existing television broadcasts.
As mentioned above, to provide data broadcasting service mainly to mobile units and portable terminals, it is demanded to realize various program formats which have been difficult in the existing infrastructure, and provide adequate services depending on the status of use of the viewers so that desired information may be obtained whenever and wherever requested.